Bad news, trick-or-treaters: A new recommendation from the World Health Organization (WHO) deals a serious blow to your annual candy binge. The guideline, set to be released this fall, drops the suggested daily intake of "free sugars"—those added to processed foods, such as high-fructose corn syrup, and those that result when naturally occurring sugars are refined, as with maple syrup.

"Even orange juice contains added sugar because it's very concentrated," says WHO adviser Chessa Lutter. Ideally, free sugars should make up a mere 5 percent of one's daily calories. For a fairly active 10-year-old, that's about 23 grams per day, or 5.8 teaspoons. And that translates to a paltry haul of candy.